The correct answer is- transverse tubules.
Transverse tubules are the membranous channel that extends inward from the muscle cell, these are the actually the addition or extensions of the cell membrane that invade into the center of muscles cells except smooth muscles.
The role of the transverse tubules is to generating the stimulus or signals from the sarcolemma to down in the cell. Sarcolemma are the surface of the cells in muscles.
Thus, the correct answer is - transverse tubules.
Membranous channel extending inward from muscle fiber membrane , is the transverse tubules.
Transverse tubules -
Transverse tubules also called the T - tubules , are basically the extensions of the cell membrane that penetrates into the center of the skeletal and the cardiac muscle cells .
T - Tubules are made up of phospholipid bilayer .
T - Tubules are directly connected to the sarcolemma at one of the end , forming a network of the tubules running parallel and perpendicular to the sarcolemma.
membranous channel extending inward from muscle fiber membrane